Calender roll assembly



C. M. WESTBROOK CALENDER ROLL ASSEMBLY Nov. 19, 1963 Filed Jan. 13, 4 1962 v BY ww %w- A RNEYS 2 Sheets-Sheet 1 I NVEN TOR. [fir/M Wasp 170m Fatented Nov. 19, 1963 3,111,081 CALENDER ROLL ASSEMBLY Carl M. Westbrook, Beloit, Wis., assignor to Belo t Iron Works, Beloit, Wis., a corporation of Wisconsin Filed Jan. 18, 1962, Ser. No. 168,024 18 Claims. (Cl. 100-93) This invention relates to the corrective control of a roll subject to dissymmetry or bowing, with the resultant whipping of the roll as its rotates.

Although the instant invention may be useful in a number of arts, it is particularly useful in the paper machine art for correcting the whipping or bowing of calender rolls subject to loads or other conditions which tend to deflect the rolls centrally to one side of the axis of rota tion of the roll or which tend to cause the roll to whip as it rotates. The application of the invention to the correction of bowing or whip of calender rolls will, therefore, herein be described although the invention is equally useful in correcting the whipping and resultant whip of the wire returning rolls in Fourdrinier paper machines and the whipping of various other rolls used in the paper machine and other arts.

In calender stacks, the paper web passes through a nip between a pair of superimposed rolls, subjecting the web to pressure. The pressure thus applied at the nip tends to load the rolls and deflect or bow the rolls, resulting in an undesirable application of forces across the nip and marking of the paper.

The marking of the paper in the calendering of the paper web is commonly referred to as bar marking and is generally caused by instability or whipping of the rolls in a multiple calender stack. This bar marking is readily evident on a web of paper and appears in the form of sets of equally spaced bars extending across the width of the web and slightly changing the sheet caliper at the bars.

This bar marking results in a change in sheet density and ink receptivity and may be caused not only by bowing of the calender roll by loading, but also by decay of residual (manufacturing) stresses, improper heat distribution along the surface of the roll, non-uniform Wall thickness, creep stresses, or a static unbalance in one or more planes of the roll body. It may further be caused by any discontinuity in hardness of the roll, producing an uneven wear or washboard effect on the roll and may be caused by corrosion or by burning a line across the face of the roll when it stalls momentarily. Also, if a roll forms a line contact with a wet or damp surface, a line of corrosion may occur across the entire face of the roll, and this line will get larger as the roll revolves against adjacent rolls, whether formed from a burn or corrosion, and will transfer to adjacent rolls until it travels up and down the entire calender stack.

Bar marking, therefore, is caused by any condition which causes a section perpendicular to the axis taken through the calender roll to be asymmetrical with respect to any centerline. a

A principal object of the present invention is to remedy the foregoing deficiencies in calender rolls by returning an asymmetrical roll to a symmetrical condition by the application of heat to sectional portions of the roll.

Another object of the invention is to correct calender roll instability by the selective heating of regions of the roll throughout the entire length of the roll during each cycle of rotation of the roll.

It is another object of the instant invention to provide an improved roll assembly, wherein the simple expedient of temperature control of sectional portions of the roll may be used to correct instability of the roll.

' A still further object of the invention is to correct calender roll instability by providing circumferentially spaced heating elements spaced radially inwardly of the roll-face,

and by supplying heat to at least one heating element opposite the point of greatest bowing of the roll face during each cycle of rotation of the roll for the duration of the whip phase of the roll, to thereby gradually eliminate bowing or whip of the roll.

Still another object of the invention is to provide a calender roll subject to bowing with a plurality of internal cir-cumferentially spaced heating elements extending the full length of the roll, by sensing bowing of the roll and supplying heat energy to a heating element opposite the point of maximum bowing of the roll during each cycle of rotation of the roll.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings wherein:

FIGURE 1 is a diagramatic view, diagrammatically showing a calender stack;

FIGURE 2 is an essentially diagrammatic side view of a roll assembly embodying the invention with certain parts broken away and certain other parts shown in longitudinal section;

FIGURE 3 is a diagrammatic transverse sectional view taken through the roll shown in FIGURE 2;

FIGURE 4 is a diagrammatic wiring diagram illustrating the means for detecting, mowing or whip of the calender roll diagrammatically shown in FIGURE 1;

FIGURE 5 is a diagrammatic view illustrating another form of bowing or whip detecting means from that shown in FIGURE 4;

FIGURE 6 is a diagrammatic View of a modified form of bowing or whip'sensing device from those shown in FIGURES 4 and 5;

FIGURE 7 is a sectional view taken through a modified form of roll constructed in accordance with the invention; and

FIGURE 8 is a sectional view taken through a further modified form of roll. 7

- In FIGURE 1 of the drawings, I have diagrammatically shown a calender stack 10 comprising a king roll 11 at the bottom, a calender roll 12 in nip defining relation with respect to the king roll and a series of pressure and calender control rolls 15 in nip defining relation with respect to each other, the lower of which rolls is in nip defining relation with respect to the calender roll 12.

The calender roll 12 may be made from metal such as cast iron and has a cylindrical peripheral face 13 and a central bore 15 extending for the length thereof having an internal cylindrical wall 16; The calender roll 12 also has a shaft 17 extending from the left hand end thereof. The shaft 17 may be'hollow and may have communication with the hollow interior of the roll 12. A pressure fitting 18 is shown as being on the end of the shaft 17 to accommodate the supply of fluid under pressure to the hollow interior of the drum 16 for purposes which will hereinafter more clearly appear as the specification proceeds.

A shaft 19 projects from the right hand end of the roll '12 and has a conductor ring 20 mounted thereon and spaced conductor segments 21'spaced axially from the conductor ring '20 and mounted to extend about the shaft 19.

Within the hollow interior portion of the roll 12 is a hollow expausible heat resistance tube 23. The tube' the outer periphery thereof. The heating elements 25- may be segmental in form and may be resistor types of heating elements in which resistors 22 are carried in segmental insulators 28, although they need not be resistor types of heating elements, but may be of various well known forms.

The heat resistant expansible tube 23 with the heating elements 25 may be inserted into the hollow interior portion of the roll 12, with the heating elements 25 in engagement with the internal cylindrical wall 16 of said roll. The roll 12 maybe sealed to and closed at one end by the shaft 19. The end of said roll adjacent the hollow shaft 17 may be open and may have fluid cominu'nication with the hollow interior portion of said shaft. As the heat resistant expansible tube 23 with its heating elements 25 is inserted in position in the hollow interior portion of the roll 12, it may be expanded by air or liquid admitted through the pressure fitting 18 until the electrical heating elements 25 molded therein are pressed into tight contact with the interior cyindrical wall 16 of the roll 12. The fitting 18 may have suitable valve means (not shown) therein retaining fluid under pressure within the hollow expansible heat resistant tube 23, to maintain the heating elements 25 in tight contact with the internal cylindrical wall 16 of the roll 12, during operation of said roll. The means for energizing selective heating elements 25 includes the conductor ring 20, shown as being engaged by a brush 26. The conductor ring 20 serves as a common electrical conductor having connection with all of the heating elements 25. The segmental conductor ring 21 is shown as being engaged by a brush 27. Each segment of the segmental conductor ring 21 has electrical connection with an electric heating element 25 and completes a circuit through a heating element 25 as the brush 27 is connected to a source of electric power and has contact with a segment of the segmental conductor 21.

A deflection or whip detector is provided for energizing certain segments of the segmental conductor ring 21 during each cycle of rotation of the roll 12, and to determine which circumferential sector of the roll 12 should be heated in order to correct for dissymmetry. The deflection or whip detector is shown in FIGURE 4 as being in the form of a pickup or transducer 29, which may contact the surface of the roll 12 adjacent the center of the roll, and in a horizontal plane extending through the axis of rotation of the roll.

It should here be understood that since the top and bottom portions of the roll 12 are contacted by other calender rolls, bowing or whipping generally takes place in a horizontal plane, where the roll is an intermediate calender roll.

The transducer or pickup 29 may be of a conventional form commonly used to pick up vibrations in shafts or rolls and is no part of the present invention, so need not herein be shown or described further.

The pickup 29 is connected with a source of power through a conductor 30 and has connection with a coil 31 of a relay 32 through a conductor 33. The coil 31 is connected to a main line conductor 35 through a conductor 36, and is energized upon the completion of a circuit through the transducer 29, effected by whip of the roll 12. Energization of the coil 31 will close contacts 37 of the relay 32 and complete a circuit through a conductor 38, to the brush 27 The brush 27 is shown as being located in diametrically opposed relation with respect to the pickup 29 to effect the flow of current through a heating element 25 directly opposite from the point of maximum deflection or whip of the roll 12. The contacts 37 of the relay 22 thus close at the point or maximum deflection of the roll '12 by the closing of a circuit through the pickup 29 and open as the point of maximum bowing of the roll #12 passes the pickup 29. Thus, during each revolution of the roll 12 the contacts 37 are closed 'as bowing of the roll is picked up by the pickup 29, to momentarily energize the heating element 25 and heat a segment of the roll 12 only during v 4 the period of the pickup senses the bowing or Whip of said roll.

It should here be noted that at high speeds the cur-rent may flow through an individual heating element for a relatively short time. Only a few degrees of corrective heat, however, are required to cure the whip and bring the roll into symmetry.

In FIGURE 5, I have shown \a modified form of system for supplying an amount of electrical energy to a selective heating element 25 in the roll 12, which is proportional to the amount of bowing or Whip of the roll. In this form of energizing and detection system, the bowing or whip sensing means is in the form of a conventional capacitance transducer 39. The capacitance transducer 39 has a sensing element which basically is in the form of a metallic sensing plate 40 located a fixed distance from the face of the roll 12. As for example, assuming the maximum expected bowing or whip of the roll 12 to be one-eighth inch, the spacing of the metallic sensing plate 40 from the roll face may be one-founth of an inch.

The capacitance transducer 39 may be of a commercial form, and is well known to those skilled in the art so need not herein be shown or described in detail. The capacitance transducer 39 may have such characteristics that its output is maximum when the distance between the roll face and metallic plate 40 is one-eighth inch and is minimum when the distance is one-quarter inch. The relation between maximum and minimum output would then be a linear function of the distance. The capacitance transducer is shown as being connected to a phase control 41 equipped with a silicon controlled rectifier 42. The input of the silicon controlled rectifier 42 is connected to an alternating current power supply through a conductor 43. The output of the silicon controlled rectifier phase control is connected to a heating element 25 through the brushes 26 and 27. The silicon controlled rectifier 42 and the phase control 41 are also commercial products available to the public, so need not herein be shown or described.

With this arrangement of sensing and energizing control for the heating elements 25, an amount of electrical energy is supplied to the heating element opposite the bowing or whip senser during each cycle of rotation of the roll, which is proportional to the amount of whip in the roll.

In the modified form of sensing bowing or whip of the roll 12 shown in FIGURE 5, a differential transformer 45 has been substituted in place of the capacitance transducer 39. The differential transformer 45 employs a sensing wheel 46 riding on the face of the roll. The differential transformer is connected to a phase control like the phase control 41 and to a silicon controlled rectiher like the silicon controlled rectifier 42, as in a system illustrated in FIGURE 4. The differential transformer 45 is a standard article of manufacture and gives out a signal proportional .to the amount of whip sensed by the sensing wheel 46, like the capacitance transducer diagrammatically illustrated in FIGURE 4.

In sensing the whipping or bowing of journalled rolls such as table rolls in Fourdrinier the bowing or whip sensing device may be located at any convenient position around the roll periphery. The brush 27, however, should be located from the sensing device.

In the form of the invention illustrated in FIGURE 7, I have shown a thin metal expansible tube in the form of a scarfed tube 50, for maintaining the segmental heating elements 25 into tight engagement with the internal wall 16 of the roll 12. The tube is shown as being held in its expanded condition by expansible spring snap rings 51. The tube 50 may, however, be expanded by fluid under pressure, and in various other conventional manners.

In FIGURE 8, a series of opposed semi-cylindrical shoes 53 are positioned within the roll 12 in end to end relation to press the heating elements 25 into engagement with the wall 16. The shoes 53 have tapered inner surfaces 55 engaged by frusto-conical wedges 56, and expanded by said wedges to maintain the heating elements 25 into engagement with the internal wall .16. The Wedges 56 are held from rotation in a suitable manner and are illustratively shown as being threaded on a threaded rod 57, held from translational movement and rotated by a wrench or crank (not shown) to move the Wedges 56 along the tapered Walls 55 of the shoes 53, and expand said shoes in an obvious manner.

It should here be understood that while I have herein described the heating elements as being electrically energized heating elements, that they need not be such heating elements and that steam or hot ilu-id may be used as a heating means and flowed through the selected passageways extending along the inside of the outer shell, under control of an electrically energizable valve (not shown) taking the place of the relay 32.

It may be seen from the foregoing that a simplified means has been provided for correcting instability in a roll in which heat under the control of the deflection of the roll is supplied along the portion of theroll opposite its region of greatest whip during each cycle of rotation of the roll.

It may further be seen that the corrective means of the invention may be used to correct bowing or whip of various types of rolls and that the sensing of bowing of the roll 'eifects the heating of the portion of the roll opposite its point of maximum whip or bowing during each cycle of rotation of the roll, until the bowing or Whip of the roll has been gradually eliminated.

While I have herein shown and described one form in which my invention may be embodied, it may readily be understood that various variations and modifications in the invention may be attained without departing from the spirit and scope of the novel concepts thereof as de fined by the claims appended hereto.

I claim as my invention:

l. A roll subject to whip on the peripheral generally cylindrical surface thereof,

(a) said roll being divided into heat-responsive segmental sections, each section extending substantially the length of the roll,

(b) and means for selectively creating a temperature differential between one of such segmental sections and the other of such sections to correct for whip in the peripheral surface of the roll.

2. A method of curing whip of a roll comprising the steps of (a) sensing the roll face along the transverse center thereof to detect whip of the roll,

(b) internally heatinga region of the roll, opposite the point of greatest whip of the roll face sensed, for substantially the length of the roll face during each cycle of rotation of the roll, for the duration of the whip phase.

3. A method of curing whip of a roll comprising the steps of (a) sensing the roll face along the transverse center thereof to detect whip of the roll,

(b) internally heating a segment of the roll opposite the point of greatest whip sensed, for substantially the length of the roll face for the duration of the whip phase.

4. A roll subject to whip having:

(a) a generally cylindrical peripheral roll face,

(b) a plurality of internal circumferentially spaced heating elements spaced radially inwardly of said roll face,

(0) a whip sensing device cooperating with said roll face,

(d) a source of heat energy,

(e) means supplying heat energy from said source of supply of heat energy to a heating element opposite the point of maximum whip of the roll,

(f) and means actuated by said whip sensing device for successively providing communication between said source of supply of heat energy and a heating element diametrically opposed to said whip sensing device.

5. A roll subject to whip comprising:

(a) an outer shell having a generally peripheral roll face,

(b) a plurality of internal circumferentially spaced electric heating elements spaced radially inwardly of said roll face and extending along said roll face for substantially the length thereof,

(c) a whip sensing device cooperating with said roll face,

(d) a source of supply of electric energy,

(2) means for supplying electric energy from said source of supply of electric energy to a heating element opposite said whip sensing device including (1) means energized by said heat sensing device for successively connecting the heating element opposite the point of greatest Whip of the roll with said source of supply of electrical energy during each cycle of notation of said roll.

'6. A roll subject to whip comprising:

(a) an outer shell having a peripheral roll face,

(b) an inner shell having a plurality of circumferentially spaced heating elements therein,

(0) and means for successively supplying heat to at least one heating element opposite the point of maximum whip of roll face during each cycle of rotation of the roll for the duration of the whip phase.

7. A roll subject to whip comprising:

(a) an outer shell having a cylindrical peripheral roll face,

(b) an inner shell having (c) a plurality of circumferentially spaced electric heating elements carried by said inner shell and extending for substantially the length thereof,

(d) and means for successively energizing a heating element opposite the point of maximum whip of the roll face during each cycle of rotation of the roll.

8. A roll subject to whip comprising:

(a) an outer shell having a cylindrical peripheral roll face,

(b) an inner shell,

(c) a plurality of circumferentially spaced heating elements carried by said inner shell and extending therealong,

(d) a whip sensing device cooperating with said roll face,

(e) a source of heat energy,

(1) and means actuated by said whip sensing device for providing communication between said source of heat energy and a heating element opposite said whip sensing device, during each cycle of rotation of the roll and for the duration of the whip phase of the roll.

9. A roll subject to whip comprising:

(a) an outer shell having a cylindrical peripheral roll face,

(b) an inner shell,

7 (c) a plurality of segmental circumferentially spaced electrically energizable heating elements carried by said inner shell and extending for substantially the length thereof,

(d) a source of supply of electric energy,

(e; a whip sensing device cooperating with said roll ace,

(1) means activated by said whip sensing device for connecting an electrically energizable heating element opposite said Whip sensing device with the source of supply of electric energy during each cycle 7 of rotation of the roll for the duration of the whip phase of the roll.

10 A roll subject to whip comprising:

(a) an outer metallic shell having a cylindrical peripheral roll face and having an internal cylindrical face,

(b) an inner expansible shell extending along said outer shell and carrying a plurality of circumferentially spaced heating elements, extending therealong for substantially the length thereof, and retaining said heating elements into engagement with said internal cylindrical face,

() means for sensing whip of said outer shell,

(d) and means activated by said sensing means for successively supplying heat to a heat element diametrically opposite the point of greatest whip of the roll during each cycle of rotation of the roll for the duration of the whip phase of the roll.

11. A roll subject to whip comprising:

(a) an outer hollow shell having a cylindrical peripheral roll face and an internal cylindrical wall, (12) an inner hollow expansible shell within said outer shell,

(0) a plurality of circumferentially spaced heating elements carried by said inner shell and extending therealong for engagement with said internal cylindrical Wall of said outer shell,

(d) means for expanding said inner shell to press said heating elements into engagement with said internal cylindrical wall,

(e) whip sensing means for detecting whip of said roll face,

(f) and means activated by said whip sensing means for supplying heat to at least one heating element opposite the point of maximum whip of the roll face during each cycle of rotation of the roll for the duration of rotation of the roll.

, 12. A roll subject to whip comprising: (a) an outer shell having a cylindrical roll face and an internal cylindrical wall,

(b) an inner expansible shell within said outer shell,

extending for substantially the length thereof,

(c) a plurality of circumferentially spaced heating elements carried by'said inner shell and extending for substantially the length thereof,

(d) fluid inlet means connected with said inner shell for supplying fluid under pressure to the hollow intcrior thereof to expand said shell and press said heating elements into tight engagement with said internal cylindrical wall,

(2 a whip sensing device cooperating with said roll ace,

(1) a source of electric energy,

(g) and means activated by said whip sensing device for connecting said source of electric energy with a heating element diametrically opposite said whip sensing device during each cycle of rotation of the roll for the duration of the whip phase.

13. In a roll subject to whip,

(a) an outer shell having a cylindrical peripheral roll face and an internal cylindrical wall,

(12) a hollow expansible shell within said outer shell,

(0) a plurality of circumferentially spaced heating elements carried by said inner shell extending outwardly therefor into position to engage said internal cylindrical wall,

(:1) and means for expanding said inner shell to press said heating elements into tight engagement with said internal cylindrical wall.

14. In a roll subject to whip,

(a) an outer shell having a cylindrical peripheral roll face and an internal cylindrical wall,

(17) a hollow expansible metal shell within said outer shell,

(0) a plurality of segmental heating elements extending along the periphery of said inner shell for substantially the length thereof,

(d) and means for expanding said inner shell to press said heating elements into tight engagement with said internal cylindrical wall,

15. In a roll subject to whip,

(a) an outer shell having a cylindrical peripheral roll face and an internal cylindrical wall,

(b) a hollow expansible metal shell Within said outer shell,

(0) a plurality of segmental heating elements extending along the periphery of said inner shell for substantially the length thereof,

(d) and means for expanding said inner shell to press said heating elements into tight engagement with said internal cylindrical wall,

(e) and other means for heating a heating element opposite the point of greatest Whip of the roll during each cycle of rotation of the roll.

16. A roll subject to whip on the peripheral generally cylindrical surface thereof,

(a) said roll being divided into heat-responsive segmental sections disposed internally of the peripheral generally cylindrical surface of the roll, each section extending substantially the length of the roll,

(b) and means for selectively creating a temperature differential between one of such segmental sections and the other of such sections to correct for whip in the peripheral surface of the roll.

17. In a calender stack, a top roll and at least one other calender rolll subject to a load in the stack,

(a) said other roll being subject to dissyrnmetry and having a peripheral generally cylindrical surface and being divided internally of said peripheral generally cylindrical surface into heat-responsive segmental sections, each section extending substantially the length of the roll,

(12) and means for selectively creating a temperature differential between one of such segmental sections and the other of such sections to correct for dissymmetry in the peripheral surface of the roll.

18. In a calender stack, a top roll and at least one other calender roll subject to a load in the stack References Cited in the file of this patent UNITED STATES PATENTS Boyd Aug. 20, 1935 Youngchild July 25, 1961 

1. A ROLL SUBJECT TO WHIP ON THE PERIPHERAL GENERALLY CYLINDRICAL SURFACE THEREOF, (A) SAID ROLL BEING DIVIDED INTO HEAT-RESPONSIVE SEGMENTAL SECTIONS, EACH SECTION EXTENDING SUBSTANTIALLY THE LENGTH OF THE ROLL, (B) AND MEANS FOR SELECTIVELY CREATING A TEMPERATURE DIFFERENTIAL BETWEEN ONE OF SUCH SEGMENTAL SECTIONS AND THE OTHER OF SUCH SECTIONS TO CORRECT FOR WHIP IN THE PERIPHERAL SURFACE OF THE ROLL. 